Compressor and method



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COMPRESSOR AND METHOD 3 Sheets-Sheet 2 llllllll llflllllll l IIIIIIIIIF'I l I A Fore: Wl/JO/7 INVENTOR. am 7 WM; y d z/f 24M 2 fid 6 9m,

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Wl/JOI? INVEN'IUR. y W; W M By ,L/Dehl pa g K121i United States Patent 3,349,996 COMPRESSOR AND METHOD Forbes Wilson, 3820 Meadowlake,

Houston, Tex. 77027 Filed Feb. 24, 1966, Ser. No. 529,741 'Claims. (Cl. 230-52) This application is a continuation-in-part of Serial No. 121,475, filed July 3, 1961, now Patent No. 3,237,847 granted March 1, 1966.

The present invention relates to improvements in compressors for and methods of compressing gases.

It would be desirable to provide a compressor for gas and a method of compressing gas in which the energy source therefor is any convenient source of external heat directly applied or used thereby giving almost complete freedom of choice of fuels and allowing waste heat to be used in all or in part for further economy. By applying the external source of heat directly to the compressor or directly in the method without first converting this energy, the compressor and method can be operated from a convenient and nearby source of available heat without an outside additional drive being necessarily required.

It would also be desirable to provide such a compressor for gas and a method for compressing gas in which increased compression is obtained and, at the same time, the discharged compressed gas has been cooled. The present invention is directed to such a compressor and method.

It is therefore an object of the present invention to provide a compressor for and a method of compressing gas in which the direct application of heat from a convenient external source is utilized to drive the compressor and operate the method, at least in part, and in which relatively high compression is obtained and the compressed gas discharged has been cooled.

Yet a further object of the present invention is the provision of such a compressor for and a method of compressing gas which is actuated by the direct application of heat from any convenient source of external heat and in which no outside engine or other driver is required.

Still a further object of the present invention is the provision of such a compressor and method in which the gas being compressed serves as its own working medium by the application thereto of heat from any convenient source of external heat.

.Yet a further object of the present invention is the provision ofa compressor for and a method of compressing gas in which the gas is first mechanically compressed, then heated at a substantially constant volume thereby increasing its pressure, the heated gas then being combined with cooler liquified gas effecting heat transfer to the liquified gas which heats and gasifies all or part of the liquified gas under substantially restricted volumetric conditions thus raising the pressure of the mixture above the pressure of the heated gas and lowering the temperature of the heated gas, the now largely homogenous gas then being expanded and the energy from this expansion being used to provide substantially toward the actuation for the mechanical compression. Preferably, this energy is utilized as the entire actuation of the mechanical compression, although more or less energy as required may be developed by the expansion phase. A portion of the exhaust gas from the expansion phase is passed through a condenser which is cooled by any convenient coolant so that this portion is liquified and then is pumped to an elevated pressure or is carried as a gas to an elevated condenser so that when liquified it will have an elevated pressure suflicient to inject it into combination with the ice aforesaid heated gas. The other portion of the exhaust gas is the finally compressed gas.

Still a further object of the present invention is the provision of such an improved compressor for and a method of compressing gas in which a portion of the discharge gas from the mechanical compressor is conducted to the condenser which is cooled by any convenient coolant so that this gas is liquified and then its pressure is elevated sufficient to inject it into combination with the heated gas which, being in a subsantially restricted volume, raises the pressure of the heated gas by gasifying the liquified gas, the now largely homogenous gas then being expanded and the energy used in mechanical compression is previously described, the exhaust gas from the expansion phase being the finally compressed gas.

Still a further object of the present invention is the provision of such an improved compressor for and a method of compressing gas in which all of the discharge gas from the mechanical compressor is conducted to the condenser which is cooled by any convenient coolant so that this gas is liquified and its pressure is elevated sutficient to inject it into combination with the residue exhaust gas in the heater which, being in a substantially restricted volume, raises the pressure of the heated gas, the now largely homogenous gas then being expanded and the energy used in mechanical compression as previously described, the surplus or non residue exhaust gas from the expansion stage being the finally compressed gas.

Other and further objects, features and advantages will be apparent from the following description of presently preferred embodiments of the invention, given for the purpose of disclosure, and taken in conjunction with the accompanying drawings, illustrating apparatus according to the invention and satisfactory for use in the method of the invention, where like character references designate like parts throughout the several views and where FIGURE 1 is a diagrammatic sectional view, in elevation, illustrating a compressor according to the invention.

FIGURE 2 is a view of the compressor of FIGURE 1 with the parts in a position further along in the cycle,

FIGURE 3 is a View similar to that of FIGURES l and 2 with the parts in a still further position during the cycle,

FIGURE 4 is a view similar to that of FIGURES l-3, inclusive, with the parts in a still different position during the cycle,

FIGURE 5 is a pressure-enthalpy diagram illustrating the general mode of operation of a compressor according to the invention in which a portion of the expander exhaust gas is condensed and liquified,

FIGURE 6 is a pressure-enthalpy diagram illustrating the general mode of operation of a compressor according to the invention in which a portion of the discharge gas from the mechanical compressor is condensed and liquified, and

FIGURE 7 is a pressure-enthalpy diagram illustrating the general mode of operation of a compressor according to the invention in which all of the discharge gas from the mechanical compressor is condensed and liquified.

In FIGURES 5, 6 and 7, the general principles and modes of operation of the various forms of the compressors are illustrated. In these figures, enthalpy is plotted as the abscissa and pressure as the ordinate. The enthalpy values increase to the right and the pressure values increase to the top, as the graphs are viewed. Also plotted by the lines labeled as such are constant entropy and constant volume.

The lines plotted on the graphs illustrate the principles and modes of operation as mentioned. Thus, gas under suction conditions enters the compressor at point a and is mechanically compressed to an elevated pressure condition indicated by the reference letter b. The energy r quired for compression is represented by the difference in enthalpy between conditions a and b. These principles and mode of operation are common to all of the variations shown in FIGURES 5, 6 and 7.

pansion of the gas is represented by the difference in enthalpy between conditions d and e. A portion of the gas at e is discharged from the compressor, the cycle starting over again. The remaining portion of the gas at e is condensed to f, pumped as a liquid to elevated pressure at g and then injected into the gas to gasify and form the mixed gas at condition d as previously described.

In FIGURE 6 a portion of the gas at b is heated at a substantially restricted volume where it attains the pres-' sure indicated by the letter 0. The gas is then combined with the cooler liquified gas provided at relatively elevated pressure. This mixture is then expanded and the energy utilized as previously described. In this variation, all of the gas at e is discharged from the compressor, the cycle starting over again. The remaining portion of gas at b is condensed to f, pumped or otherwise raised as a liquid to elevated pressure at g and then injected into the gas c'to gasify and form the mixed gas at condition 0! as previously described.

In FIGURE 7, all of the gas at b is condensed to f, pumped as a liquid to elevated pressure 3 and then injected into gas c to gasify and form a mixed gas at condition d as previously described. The combined gaseous mixture is then expanded and the energy utilized as previously described. In this variation a portion of the gas at e is discharged from the compressor, the cycle starting over again, the remaining portion of the gas at condition e is heated at a substantially restricted volume so that it attains the pressure indicated by the letter 0. It is then mixed with liquified gas to form condition d as previously described.

When the work output of the expansion phase, represented by the enthalpy difference de times the weight of gas expanded, is equal to or greater than the work input initially required in initially compressing the gas, represented by the enthalpy diiference ba times the weight of gas mechanically compressed, the compression is selfactuating. If the converse occurs, external work is required to assist in the drive.

Thus, the general mode of operation of the compressor comprises mechanically compressing the gas to elevate its pressure, further increasing the pressure of all or part of the gas by heating by the direct application of heat from an external source of heat while restricting the volume of this gas, condensing all or part of the gas, pumping or otherwise raising liquified gas to an elevated pressure, gasifying the liquid gas by injection into the heated gas in a restricted volume thus raising the pressure and cooling the heated gas and then expanding these gases to provide the desired or available mechanical energy for the system. The condensation step may occur before, after or in parallel with the heating step as described.

By direct application of heat is meant application of heat without first converting it to some other type of energy and includes all types of heating, such as direct, indirect, or generating heat in situ.

Referring now to FIGURE 1, a presently-preferred form of a compressor generally designated by the reference numeral 10 is illustrated. The compressor 10 includes the compression cylinder 12 and expansion cylinder 14 provided with the compression piston 16 and expansion piston 18, respectively, which are linked together by the crank arrangement 20. As illustrated, the compression cylinder 12 and expansion cylinder 14 are oriented approximately deg. apart, although other orientations may be utilized, and through the crank linkage 20 the pistons 16 and 18 move so that a substantially constant volume of gas is maintained during the heating step as hereinafter described.

For the purpose of illustration, only a single compression cylinder 12 and compression piston 16 are shown connected through the crank system 20 to a single expansion piston 18 in the single expansion cylinder 14. It will be understood, of course, that any number of these members may be utilized as desired.

A gas inlet 20 is provided into the upper portion of the compression cylinder 12 and a check valve 22 is provided which permits gas to enter the inlet 20 but prevents it from escaping therethrough.

The upper end of compression chamber 12 is connected by the passage 24 to a check valve 30 which permits gas to leave the outlet 24 but prevents it from returning to the compression chamber. The outlet of check valve 30 is connected by the passage 28 which splits into three passageways each connected to a valve which is operable by any convenient automatic means not illustrated.

One fork of the passage 28 connects to a valve 50 which connects to a passage 52 which is the gas outlet conduit from the compressor system.

Another fork of the passage 28 connects to a valve 46 which connects to a passage 54 leading to the regenerator 26.

Confined within the regenerator 26 may be a plurality of particles, segments or passageways 32 for the purpose of retaining or exchanging heat and assisting in heating gas compressed in the compression cylinder 12.

A heatre 34, here shown of the indirect type, is connected to the regenerator 26 by means of the heater tubes 36 which provide a passage for the gas from the regenerator 26 to the passage 38 into the expansion cylinder 14. The heater 34 is provided with the heat inlets and outlets 40 and 42 and preferably with the baffie 44 so that heat from any convenient external source may be brought into indirect heat exchange relationship with the gas passing through the heater tubes 36. The passages 24, 28, valves 30 and 46, passage 54, heater tubes 36 and passage 38 thus form a passage connecting the compression cylinder or chamber 12 with the expansion cylinder or chamber 14 through the heater 34.

The third fork of the passage 28 connects to a valve 48 which is connected to a condenser 58 by a passage 56. The condenser is shown as a finned tube air cooled type for convenience only, but obviously may be of any type, open or enclosed, using direct or indirect application of a coolant. A passage 60 conducts the liquified gas to a pump 62 which elevates the pressure sufficiently to inject the liquid through a valve 66 and a passage 68 into the regenerator 26, or into the passage 38, or into the heater 34, though this would be more convenient with a direct type heater than with the indirect type of heater illustrated. Some means of controlling hydraulic pulsation and liquid storage may be provided in the passage 64 which has not been illustrated in order to simplify the disclosure.

While not described in detail, obviously, suitable frame, body members, fly wheels and the like may be utilized and provided to make a completely operable compressor.

In the operation of the compressor illustrated in FIG- URES l-5 inclusive, and with reference first to FIG- URE l, the compressor piston 16 is moving in the direction of the arrows and is part way through its suction 5, stroke causing gas to be compressed to enter the compression cylinder 12 through the open check valve 22 and inlet 20. The check valve 30 has closed the passage 28 from the compression cylinder 12, being actuated by the lower pressure in the passage 24 below it.

At the same time the valve 66 is closed and the expansion piston 18 has just completed its expansion stroke and is beginning its displacement stroke causing heated and expanded gas in expansion cylinder 14 to begin moving back through the passage 38, heater tubes 36, regenerator 26, and out to the fork in the passage 28 through the connecting passage 54 and the valve 46 which is open. From the passage 28, a portion of the gas is discharged from the compressor through the valve 50, which is open, and the passage 52. The remaining portion of the gas is transmitted to the condenser 58 through the open valve 48 and the connecting passage 56.

The relative volumes of the portions of gas going to each outlet from the passage 28 may be controlled in a variety of ways including but not limited to; valve timing, valve and passage sizing, condenser sizing, coolant effectiveness and pump sizing, none of which control mechanisms are illustrated.

The three valves, 46, 48 and 50' can be designed as one vlave to function in a similar fashion but are shown as separate valves for simplification in the illustration.

Heat is removed from the gas in the condenser 58 until it liquifies. The liquified gas is stored during this part of the cycle at any convenient point between the condenser 58 and the valve 66 which is closed.

Referring now to FIGURE 2, the continuation of the cycle is illustrated in which the compression piston 16 is now in position to begin its compression stroke, thus closing the check valve 22, the expansion piston continuing its movement from FIGURE 1 and continuing to force the hot expanded gas through the heater tubes 36, the regenerator 26, connecting passage 54, open valve 46, passage 28, and open valves 50 and 48, as previously described.

FIGURE 3 illustrates the parts in a next phase of the cycle with the compression piston 16 partially through the compression stroke and the expansion piston 18 having completed its displacement stroke. Since the incoming gas has been compressed to a pressure slightly greater than the pressure in the passage 28, the check valve 30 opens to the passage 28 and the incoming gas is directed through the valve 46 and the connection 54, through the regenerator 26 and the heater 34 and into the expansion cylinder, the valves 48 and 50 now being closed. As the gas passes through the regenerator 26 it is initially heated by the particles or segments 32 previously heated by the hot gas just discharged and is further heated in passing through the heater 34. As previously explained, since the incoming gas has been mechanically compressed by the compressor 16 to elevate its pressure, it is then heated at a nearly constant volume which causes its pressure to be increased, as previously described in connection with the graph of FIGURE 5.

Referring now to FIGURE 4, a further phase of the compression cycle is illustrated in that the compression piston 16 has completed its compression stroke causing the mechanically compressed gas to flow through the open valve 46, being blocked 'by closed valves 48 and 50, through the regenerator 26 and the heater 34, as previously described, into the expansion cylinder 14. In this connection, a comparison of the position of the parts in FIGURES 3 and 4 illustrates that the volume above the compressor piston 16 and above the expansion piston 18 remains nearly constant in the time interval between the movement of the parts from the positions illustrated in FIGURE 3 to those illustrated in FIGURE 4. The initially compressed gas is thus further compressed by heating while confined at a substantially constant volume while confined by the passages 24, 28, 38, 46, and 54, the regenerator 26, the heater tubes 36 and the communicating portions of the compression and expansion cylinders 12 and 14, respectively. The heated gas is then combined with cooler liquified gas injected through the valve 66, which gasifies the liquid gas in the confined volume previously mentioned thus further raising the pressure of the heated gas.

The super compressed gas mixture therefore expands forcing the expansion piston 18 downwardly in the direction of the arrow thereby providing a power stroke and providing mechanical energy to actuate the piston 16 through the leverage of the crank linkage 20. At this point, as illustrated in FIGURE 4, the compression piston 16 is approximately at top dead center and does not exert any appreciable leverage to resist this motion.

A next phase of the cycle is illustrated in FIGURE 1 in which the expansion piston 18 has completed its power stroke and is starting to move upwardly and thereby forces the heated and compressed gas from the compressor 10, the compression piston 16 having begun its suction stroke, as previously described.

Thus, as previously mentioned in connection with the graph of FIGURE 5, incoming gas at point a is mechanically compressed in the compression cylinder 12 (FIG- URES 2, 3 and 4), heated in a restricted volume by the regenerator 26 and heater 34 (FIGURES 3 and 4) to further increase its pressure between points b and 0 shown in the graph of FIGURE 5, mixed with cooler liquified gas (FIGURE 4) which cools and raises its pressure from point 0 to point 0! on the graph of FIGURE 5, expanded in expansion cylinder 14 (FIGURES 4 and 1) from the point d to point e on the graph of FIGURE 5 to provide the mechanical energy or power for the compressor piston 16 and then a portion is expelled from the compressor at a pressure slightly less than the pressure at point b of the graph during the return stroke of the expander piston 18 and the suction stroke of the compressor piston 16 (FIG- URES 1 and 2). The remaining portion of expanded gas is carried to the condenser condensed (FIGURES 1, 2, 3 and 4) from the point e to point 1 on the graph of FIGURE 5. The liquified gas is then pumped to an elevated pressure and stored (FIG- URES 1, 2, 3 and 4) from point 1 to point 3 on the graph of FIGURE 5. The liquified gas is then injected into the regenerator-heater (FIGURE 4) and is gasified by mixing with the warm gas, from point g to point at on the graph of FIGURE 5 (FIGURE 4) The valves 46, 48, 50 and 66 are illustrated in FIG- URES 1, 2, 3 and 4 in the operating positions required for the type of operation shown on the graph of FIG- URE 5. Variation of the timing of the operation of these valves can alter the operation of the compressor from that shown in FIGURE 5 to the type of operation shown in FIGURE 6 and/or FIGURE 7, as previously described.

Actually, valve 46 is always open during the type of operation illustrated in FIGURE 5 and therefore is not required for this embodiment. Valve 46 is also not required in the system to be described for the operation type illustrated in FIGURE 6. Valve 46 is required for the operation shown as FIGURE 7 and is included in FIG- URES l, 2, 3, 4 since it does not detract from the simplicity of these illustrations and its presence on these illustrations will help in the later explanation of the type of operation shown in FIGURE 7.

Thus the same apparatus shown in FIGURES 1, 2, 3 and 4 can be adjusted by any appropriate valve control mechanism to operate in the general method illustrated in the graph shown as FIGURE 6. As previously mentioned in connection with the graph of FIGURE 5, the graph of FIGURE 6 illustrates a method of operation in which incoming gas at point a is mechanically compressed in the compression cylinder 12 (FIGURES 2, 3 and 4). Valve 48 is shown closed in FIGURE 3 which illustrates part of the FIGURE 5 cycle. Valve 48 is opened during the part of the cycle illustrated by FIGURE 3 for FIGURE 6 operation. All other valves remain as illus- (FIGURES 1 and 2) and is trated on FIGURES 2, 3 and 4. Thus, a portion of the gas at b is heated in a restricted volume by the regenerator 26 and the heater 34 (FIGURES 3 and 4) to further increase its pressure between points b and c shown in the graph of FIGURE 6, is mixed with cooler liquified gas (FIGURE 4) which cools and raises its pressure from point to point d on the graph of FIGURE 6. The other portion of the gas at point b is condensed in condenser 58 to a liquid phase shown as point f on FIGURE 6, is then pumped to an elevated pressure by pump 62 as shown on point g on FIGURE 6, is stored and then injected into the regenerator-heater chamber or chambers by the timely opening of valve 66 as illustrated on FIGURE 4 which mixes the cooler liquified portion of the gas with the other portion of heated gas shown at point c on FIGURE 6 which gasifies the liquid at g and forms the homogenous gas mixture illustrated as point d on FIGURE 6. The gas at point d is then expanded in expansion cylinder 14 (FIGURES 4 and 1) from the point d to point e on the graph of FIGURE 6 to provide the energy for the compression piston 16 and then is entirely expelled from the compressor at a pressure slightly lower than the pressure at point b of the graph of FIG- URE 6. All gas is expelled because valve 48 (shown open in FIGURES 1 and 2) is to be closed in these parts of the cycle for operation as illustrated in FIGURE 6. Thus, the compressor may be operated as in FIGURE 6 as compared to FIGURES 1, 2, 3, 4 and by closing the valve 48 in the parts of the cycle shown as FIGURES 1 and 2 (valve 48 is shown open at these points) and opening valve 48 in the part of the cycle illustrated in FIG- URE 3 (valve 48 is shown closed at this point). All other features of the cycle remain the same for operation as illustrated in FIGURE 6 as compared to the operation as illustrated in FIGURES 1, 2, 3, 4 and 5.

As previously described, valve 46 is open through all parts of the cycles illustrated in FIGURES 1, 2, 3, 4, 5 and 6 and therefore is not a necessary part of the apparatus for those methods of operation and could be replaced by an ample extension of conduit 54 to a point of attachment to conduit 28. As will be described, valve 46 is necessary for operation of the apparatus according to the cycle illustrated in FIGURE 7.

The same apparatus shown in FIGURES 1, 2, 3 and 4 can be adjusted by any appropriate valve control mecha nism to operate in the general method illustrated in the graph shown as FIGURE 7. As previously described in connection with the graphs of FIGURES 5 and 6, the graph of FIGURE 7 illustrates a method of operation in which incoming gas at point a is mechanically compressed in the compression cylinder 12 (FIGURES 2, 3 and 4). The valve 48 is shown closed in FIGURES 3 and 4 for the FIGURE 5 type operation. This valve is opened in FIGURES 3 and 4 for the FIGURE 7 type of operation. The valve 46 is shown open in FIGURES 3 and 4 for the FIGURE 5 type operation. This valve is closed in FIG- URES 3 and 4 for the type of cycle shown in FIGURE 7. The valve 50 remains closed in FIGURES 3 and 4 for both cycles illustrated in FIGURES 5 and 7. Thus, all of the gas at on FIGURE 7 is directed to the condenser 58 where it is changed to a liquid phase as illustrated by point 1 on FIGURE 7, and then is pumped to an elevated pressure by the pump 62 as shown by point g on FIG- URE 7, is stored and injected into the regenerator-heater chamber or chambers by the timely opening of the valve 66 as illustrated on FIGURE 4 in connection with the FIGURE 5 cycle. It should not be construed that the valve operations described occur at exactly the 90 degree quadrants illustrated, as for example the valve 66 may advantageously open at some point between the FIGURE 3 and FIGURE 4 position and may even open at the opening of valve 66 allows cooled liquified gas to be injected into the regenerator-heater where it mixes with the heated residue gas at point 0 on FIGURE 7 which causes FIGURE 3 position for a FIGURE 7 type of cycle. The

a transfer of heat which gasifies the liquid gas and raises the pressure of the gas at point 0 because of an expanding volume in a substantially restricted chamber thus changing the liquid at g and the gas at c to a homogeneous gas at point d on the graph illustrated by FIGURE 7. The gas at point d is then expanded in the expansion cylinder 14 in FIGURES 4 and 1 from the point d to point e on the graph of FIGURE 7 to provide the energy for the compression piston 16 and then a portion is expelled from the compressor during the return stroke of the expander piston 18 and the suction stroke of the compressor piston 16 shown in FIGURES 1 and 2 which also show the valve 48 in the open position for the FIGURE 5 cycle. The valve 48 will be closed in the parts of the cycle depicted in FIGURES 1 and 2 for the type of operation illustrated in FIGURE 7. The residue gas trapped in the regeneratorheater expansion cylinder volume when the valve 46 is closed in the FIGURE 3 quadrant is heated in this substantially restricted volume and so moves from point e to point 0 on the graph of FIGURE 7. Thus, the compressor may be operated as in FIGURE 7 as compared to FIGURES 1, 2, 3, 4 and 5 by closing the valve 48 at the FIGURE 1 quadrant, and keeping it closed through the FIGURE 2 quadrant, opening valve 48 in the FIGURE 3 and 4 quadrants whereas it is closed at these points in the FIGURE 5 cycle. Further, the valve 46 will be closed in FIGURES 3 and 4 in the FIGURE 7 cycle whereas this valve is open in the FIGURE 5 cycle illustrated. The valve 50 is closed in FIGURES 3 and 4 in both FIGURE 5 and FIGURE 7 cycles. The valve 66 opens in FIGURE 4 for both cycles and may advantageously open at the FIGURE 3 position in the FIGURE 7 cycle. All other features of the cycle remain the same for operation as illustrated in FIGURE 7 as compared to the operation illustrated in FIGURES 1, 2, 3, 4 and 5.

If desired, of course, the regenerator 26 may be eliminated and the incoming gas after being mechanically compressed introduced directly into the heater 34 and if desired, the gas discharged from the cylinder 14 without passing back through the heater 34. Such an arrangement is illustrated in the dotted lines of FIGURES l-4 wherein an outlet 54' connects to the passage 54. The discharge outlet 54 is placed between the expansion cylinder 14 and the heater 34 in the passage 38. The check valve 70 is added to close the discharge outlet 54' and open the passage 38 during the expansion stroke of expansion piston 18 (FIGURES 3 and 4) and to close the passage 38 and open the discharge outlet 54 during its displacement stroke (FIGURES 1 and 2).

Obviously, other apparatus configurations may be used which would dilfer in appearance from the apparatus illustrated in FIGURES 1, 2, 3 and 4 which would perform the general functions described previously and generally illustrated by the graphs, FIGURES 5, 6 and 7. For example, a double acting reciprocating piston in a single cylinder may be utilized, with the valves timed to give the expansion end an appropriate lag behind the compressor end.

In some instances there may be some difiiculty in matching up the volume of the heat exchanger alone or combined with a regenerator with the volume required by the reciprocating device. In such circumstances it may be desirable to provide two or more heaters either alone or combined with a regenerator, in which the compressed gas is alternately or sequentially introduced so that the other corresponding heater or heaters, with or without their regenerators, may have a longer period of time for heating per compression cycle.

If desired, the heat for the compressor may be formed in situ, such as provided by combustion within the system or a hot compressed gas may be introduced into the mechanically compressed gas directly to obtain the heating. Both of these may be done with or without a regenerator. A combustible mixture may be introduced into a heater 34 and provided with a spark plug and suitable sparking system, not shown, provided to periodically ignite or combust the incoming combustible mixture. In the event the gas to be compressed is combustible, it would only be necessary to introduce a source of gas containing oxygen. While not shown, of course, suitable valves and the like are provided for this particular system. The remaining parts and remaining mode of operation is the same as that described in connection with the preceding embodiments.

In some cases it may be desirable to provide a supercharger for supercharging the gas incoming to the compressor. The supercharger may be a blower or other similar device mechanically driven by the compressor or it may be driven from any outside energy source. This arrangement would be useful in compressing a larger unit volume of gas per compressor cycle.

If desired, some of the incoming gas to the compressor may be utilized to cool the expansion cylinder and then be directed back and intermingled with the suction gas. As an alternate, some of the compressed gas from the mechanical compressor may be utilized to cool the expansion cylinder and then be directed back either to the mechanical compressor suction or to the compressor discharge. Alternately, some of the liquified gas may be utilized to cool the expansion cylinder by whole or partial vaporization in a jacket surrounding the expansion cylinder.

In some cases it may be desirable to provide-a turbocharger in which all or a portion of the exhaust gas is expanded to drive a blower applied to the gas incoming to the compressor.

In order to simplify the disclosure, these various embodiments are not illustrated, but representative examples thereof are illustrated and shown in my patent, previously mentioned, which may be modified according to the present invention.

It will be understood, of course, that one or more features of the various embodiments of the invention may be utilized with any one or more of the other embodiments, the arrangements described being for convenience of disclosure and to shorten this specification and to eliminate any further figures. It will be further understood that the compressors according to the present invention may be combined with and form a part of other types of compressors.

While the method of the invention has been touched on previously, the method comprises the steps of first compressing the gas to an elevated pressure, then further compressing the initially-compressed gas by heating it while maintaining it at a substantially restricted volume, combining the heated gas with cooler liquified gas from any convenient source thus gasifying the liquid gas in a restricted volume and thus further compressing the combined gases, partially expanding the combined gases, then utilizing the energy derived from partially expanding the combined gases in initially compressing the gas, and then discharging the compressed and cooled gas. Preferably, suflicient energy is obtained to completely drive the mechanical compressor, in which event the enthalpy decrease derived in the expansion step must be equal to or greater than the enthalpy required in the compression step first mentioned. The energy derived not used for driving the system may be used for any desired purpose.

The method also encompasses combining the liquified gas.

' with residue heated gas remaining in the hot zone from the previous cycle.

The method also includes heating the gas either by direct or indirect heat exchange relationship, by generating heat in situ, such as by combustion, including heating a confined or captive gas or fluid separate from the mechanically compressed gas, rather than the mechanically compressed gas, to provide the energy for the system and includes the use of a regenerator for initially heating the newly compressed gas by the previous outgoing gas.

The method also encompasses the use of the supercharger or turbocharger for introducing a larger'volume of gas into the compression system, includes alternate heating, sequential valving and the like. The apparatus of the invention previously described are suitable for use in the method of the invention although other apparatus may be used if desired.

If desired, both the method and apparatus may be utilized as boosters for other compressors. Also, the extra energy obtained by the expansion phase, if any, may be utilized for any purpose, as desire The present invention, therefore, is well suited and adapted to attain the objects and ends and has the advantages mentioned as well as others inherent therein.

While a presently-preferred embodiment of the apparatus and the method of the invention has been illustrated for the purpose of disclosure, changes in details and arrangement of parts and in the various steps may be made which are within the spirit of the invention as defined by the scope of the appended claims.

What is claimed is:

1. A method of compressing gas comprising initially compressing the gas to an elevated pressure,

further compressing the initially-compressed gas by heating it at substantially restricted volume,

combining the heated gas with cooler liquified gas at substantially restricted volume thus gasifying the liquid gas and thereby cooling and further compressing the heated gas,

partially expanding the combined gases,

utilizing the energy derived from partially expanding the combined gases in initially compressing the gas,

and discharging at least a portion of the last-mentioned gas. 2. The method of claim 1 where a portion of the partially-expanded combined gases are condensed thereby providing the cooler liquified gas,

and

elevating the pressure of'the liquified gas so that it may be combined with the heated gas as aforesaid.

3. The method of claim 1 where a portion of the initially-compressed gases is condensed to provide the liquified gas, and

increasing the pressure of the liquified gas to combine it with the heated gas.

4. A method of compressing gas comprising initially compressing the gas to an elevated pressure,

condensing all of the initially compressed gas,

elevating the pressure of the liquified gas,

combining the liquified gas with residue heated gas from a previous cycle which had its pressure raised by heating in a restricted volume thereby gasifying the liquid gas, cooling the residue heated gas and further raising the pressure of the combined gases,

partially expanding the combined gases in such restricted volume,

utilizing the energy derived from partially expanding the combined gases in initially compressing the gas, and

discharging all of the last-mentioned gas except for the residue gas, and

heating the residue gas in a restricted volume as aforesaid.

5. A gas compressor comprising a first stage compression chamber,

a first piston head in the compression chamber,

aheater,

an expansion chamber,

a second piston head in the expansion chamber,

passage means connecting the first stage compression chamber to the expansion chamber through at least a portion of the heater,

the heater, the passage means and the communicating portions of the first stage compression chamber and the expansion chamber comprising a second stage compressor which further compresses by heating compresed gas from the first stage compression chamber,

means interconnecting the first piston head and the second piston head for movement thereof as a unit, movement of the first and second piston heads maintaining a substantially restricted volume in the heater, the passage means and communicating portions of the first stage compression chamber and the expansion chamber during the further compression of the gas by the heating in the second stage compressor,

an outlet in the compressor in fluid communication with the first stage compression chamber introducing gas to be compressed into the compression chamber,

an outlet in the compresser in fluid communication with the second stage compressor discharging compressed gas from the second stage compressor,

valve means permitting inflow and preventing outflow of the gas through the inlet and controlling the flow of gas out of the outlet, said valve means operable to close the gas outlet during compression of the gas in the first stage compression chamber and in the second stage compressor and operable to open the gas outlet upon substantial completion of partial expansion of the gas in the expansion chamber,

means for introducing relatively cool liquified gas into the second stage compressor,

whereby, the gas entering the first stage compression chamber is compressed above its initial pressure, at least part of the compressed gas from the first stage compression chamber is then further compressed by heating in the substantially restricted volume in the second stage compressor, the heated compressed gas is further compressed and cooled by the introduction of the relatively cool liquified gas thereby gasifying the liquified gas, after which the partial expansion of the compressed, mixed gas provides energy for the compressor and moves the second piston head in the expansion chamber and thereby drives the first piston head in the first stage compression chamber, then the displacement portion of the movement of the second piston head in the expansion chamber discharges at least a part of the compressed gas out of the outlet.

6. The gas compressor of claim 5 including,

a regenerator,

the passage means connecting the first stage compression chamber to the expansion chamber is connected through the regenerator and then through the heater,

the outlet in the compressor in fluid communication with the second stage compressor discharges the compressed gas through the regenerator whereby, the initially compressed gas from the first stage compression chamber moves through the regenerator and is then further compressed by heating at substantially restricted volume in the second stage compressor, and the partially expanded compressed gas moves back through the heater, then the regenerator and then out the outlet.

7. The gas compressor of claim 5 where the means for introducing relatively cool liquified gas into the second stage compressor includes,

a condenser for liquifying and cooling gas, and

means for introducing the cool liquified gas from the condenser into the second stage compressor at a pressure in excess of that of the initially compressed and heated gas in the second stage compressor.

8. The gas compressor of claim 7 including passage means conveying gas from the outlet of the compressor to the condenser thereby providing gas to the condenser which is liquified and cooled by the condenser.

9. The gas compressor of claim 7 including passage means connecting the first stage compressor to the condenser and arranged to conduct a portion of the initially-compressed gas to the condenser which is liquified and cooled in the condenser as aforesaid.

10. The gas compressor of claim 7 including passage means conducting all of the gas from the first stage compressor first to the condenser where it is liquified and then to the second stage compressor where it combines with heated compressed residue gas from a preivous cycle.

1/1957 Walter 230-116 6/1958 Webb -59 ROBERT M. WALKER, Primary Examiner. 

5. A GAS COMPRESSOR COMPRISING A FIRST STAGE COMPRESSION CHAMBER, A FIRST PISTON HEAD IN THE COMPRESSION CHAMBER, A HEATER, AN EXPANSION CHAMBER, A SECOND PISTON HEAD IN THE EXPANSION CHAMBER, PASSAGE MEANS CONNECTING THE FIRST STAGE COMPRESSION CHAMBER TO THE EXPANSION CHAMBER THROUGH AT LEAST A PORTION OF THE HEATER, THE HEATER, THE PASSAGE MEANS AND THE COMMUNICATING PORTIONS OF THE FIRST STAGE COMPRESSION CHAMBER AND THE EXPANSION CHAMBER COMPRISING A SECOND STAGE COMPRESSOR WHICH FURTHER COMPRESSES BY HEATING COMPRESSED GAS FROM THE FIRST STAGE COMPRESSION CHAMBER, MEANS INTERCONNETING THE FIRST PISTON HEAD AND THE SECOND PISTON HEAD FOR MOVEMENT THEREOF AS A UNIT, MOVEMENT OF THE FIRST AND SECOND PISTON HEADS MAINTAINING A SUBSTANTIALLY RESTRICTED VOLUME IN THE HEATER, THE PASSAGE MEANS AND COMMUNICATION PORTIONS OF THE FIRST STAGE COMPRESSION CHAMBER AND THE EXPANSION CHAMBER DURING THE FURTHER COMPRESSION OF THE GAS BY THE HEATING IN THE SECOND STAGE COMPRESSOR, AN OUTLET IN THE COMPRESSOR IN FLUID COMMUNICATION WITH THE FIRST STAGE COMPRESSION CHAMBER INTRODUCING WITH TO BE COMPRESSED INTO THE COMPRESSION CHAMBER, AN OUTER IN THE COMPRESSER IN FLUID COMMUNICATION WITH THE SECOND STAGE COMPRESSOR DISCHARGING COMPRESSED GAS FROM THE SECOND STAGE COMPRESSOR, VALVE MEANS PERMITTING INFLOW AND PREVENTING OUTFLOW OF THE GAS THROUGH THE INLET AND CONTROLLING THE FLOW OF GAS OUT OF THE OUTLET, SAID VALVE MEANS OPERABLE TO CLOSE THE GAS OUTLET DURING COMPRESSION OF THE GAS IN THE FIRST STAGE COMPRESSION CHAMBER AND IN THE SECOND STAGE COMPRESSOR AND OPERABLE TO OPEN THE GAS OUTLET UPON SUBSTANTIAL COMPLETION OF PARTIAL EXPANSION OF THE GAS IN THE EXPANSION CHAMBER, MEANS FOR INTRODUCING RELATIVELY COOL LIQUIFIED GAS INTO THE SECOND STAGE COMPRESSOR, 